Fix cert-try-verify when denied by event action
[exim.git] / src / src / tls-openssl.c
CommitLineData
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1/*************************************************
2* Exim - an Internet mail transport agent *
3*************************************************/
4
5a66c31b 5/* Copyright (c) University of Cambridge 1995 - 2014 */
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6/* See the file NOTICE for conditions of use and distribution. */
7
f5d78688
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8/* Portions Copyright (c) The OpenSSL Project 1999 */
9
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10/* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
11library. It is #included into the tls.c file when that library is used. The
12code herein is based on a patch that was originally contributed by Steve
13Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
14
15No cryptographic code is included in Exim. All this module does is to call
16functions from the OpenSSL library. */
17
18
19/* Heading stuff */
20
21#include <openssl/lhash.h>
22#include <openssl/ssl.h>
23#include <openssl/err.h>
24#include <openssl/rand.h>
f2de3a33 25#ifndef DISABLE_OCSP
e51c7be2 26# include <openssl/ocsp.h>
3f7eeb86 27#endif
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28#ifdef EXPERIMENTAL_DANE
29# include <danessl.h>
30#endif
31
3f7eeb86 32
f2de3a33
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33#ifndef DISABLE_OCSP
34# define EXIM_OCSP_SKEW_SECONDS (300L)
35# define EXIM_OCSP_MAX_AGE (-1L)
3f7eeb86 36#endif
059ec3d9 37
3bcbbbe2 38#if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
e51c7be2 39# define EXIM_HAVE_OPENSSL_TLSEXT
3bcbbbe2 40#endif
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41#if OPENSSL_VERSION_NUMBER >= 0x010100000L
42# define EXIM_HAVE_OPENSSL_CHECKHOST
43#endif
44#if OPENSSL_VERSION_NUMBER >= 0x010000000L \
45 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
46# define EXIM_HAVE_OPENSSL_CHECKHOST
47#endif
3bcbbbe2 48
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49#if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
50# warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
51# define DISABLE_OCSP
52#endif
53
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54/* Structure for collecting random data for seeding. */
55
56typedef struct randstuff {
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57 struct timeval tv;
58 pid_t p;
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59} randstuff;
60
61/* Local static variables */
62
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63static BOOL client_verify_callback_called = FALSE;
64static BOOL server_verify_callback_called = FALSE;
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65static const uschar *sid_ctx = US"exim";
66
d4f09789
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67/* We have three different contexts to care about.
68
69Simple case: client, `client_ctx`
70 As a client, we can be doing a callout or cut-through delivery while receiving
71 a message. So we have a client context, which should have options initialised
72 from the SMTP Transport.
73
74Server:
75 There are two cases: with and without ServerNameIndication from the client.
76 Given TLS SNI, we can be using different keys, certs and various other
77 configuration settings, because they're re-expanded with $tls_sni set. This
78 allows vhosting with TLS. This SNI is sent in the handshake.
79 A client might not send SNI, so we need a fallback, and an initial setup too.
80 So as a server, we start out using `server_ctx`.
81 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
82 `server_sni` from `server_ctx` and then initialise settings by re-expanding
83 configuration.
84*/
85
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86static SSL_CTX *client_ctx = NULL;
87static SSL_CTX *server_ctx = NULL;
88static SSL *client_ssl = NULL;
89static SSL *server_ssl = NULL;
389ca47a 90
35731706 91#ifdef EXIM_HAVE_OPENSSL_TLSEXT
817d9f57 92static SSL_CTX *server_sni = NULL;
35731706 93#endif
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94
95static char ssl_errstring[256];
96
97static int ssl_session_timeout = 200;
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98static BOOL client_verify_optional = FALSE;
99static BOOL server_verify_optional = FALSE;
059ec3d9 100
f5d78688 101static BOOL reexpand_tls_files_for_sni = FALSE;
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102
103
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104typedef struct tls_ext_ctx_cb {
105 uschar *certificate;
106 uschar *privatekey;
f2de3a33 107#ifndef DISABLE_OCSP
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108 BOOL is_server;
109 union {
110 struct {
111 uschar *file;
112 uschar *file_expanded;
113 OCSP_RESPONSE *response;
114 } server;
115 struct {
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116 X509_STORE *verify_store; /* non-null if status requested */
117 BOOL verify_required;
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118 } client;
119 } u_ocsp;
3f7eeb86 120#endif
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121 uschar *dhparam;
122 /* these are cached from first expand */
123 uschar *server_cipher_list;
124 /* only passed down to tls_error: */
125 host_item *host;
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126
127#ifdef EXPERIMENTAL_CERTNAMES
128 uschar * verify_cert_hostnames;
129#endif
774ef2d7 130#ifdef EXPERIMENTAL_EVENT
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131 uschar * event_action;
132#endif
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133} tls_ext_ctx_cb;
134
135/* should figure out a cleanup of API to handle state preserved per
136implementation, for various reasons, which can be void * in the APIs.
137For now, we hack around it. */
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138tls_ext_ctx_cb *client_static_cbinfo = NULL;
139tls_ext_ctx_cb *server_static_cbinfo = NULL;
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140
141static int
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142setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
143 int (*cert_vfy_cb)(int, X509_STORE_CTX *) );
059ec3d9 144
3f7eeb86 145/* Callbacks */
3bcbbbe2 146#ifdef EXIM_HAVE_OPENSSL_TLSEXT
3f7eeb86 147static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
3bcbbbe2 148#endif
f2de3a33 149#ifndef DISABLE_OCSP
f5d78688 150static int tls_server_stapling_cb(SSL *s, void *arg);
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151#endif
152
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153
154/*************************************************
155* Handle TLS error *
156*************************************************/
157
158/* Called from lots of places when errors occur before actually starting to do
159the TLS handshake, that is, while the session is still in clear. Always returns
160DEFER for a server and FAIL for a client so that most calls can use "return
161tls_error(...)" to do this processing and then give an appropriate return. A
162single function is used for both server and client, because it is called from
163some shared functions.
164
165Argument:
166 prefix text to include in the logged error
167 host NULL if setting up a server;
168 the connected host if setting up a client
7199e1ee 169 msg error message or NULL if we should ask OpenSSL
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170
171Returns: OK/DEFER/FAIL
172*/
173
174static int
7199e1ee 175tls_error(uschar *prefix, host_item *host, uschar *msg)
059ec3d9 176{
c562fd30 177if (!msg)
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178 {
179 ERR_error_string(ERR_get_error(), ssl_errstring);
5ca6d115 180 msg = (uschar *)ssl_errstring;
7199e1ee
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181 }
182
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183if (host)
184 {
185 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection (%s): %s",
186 host->name, host->address, prefix, msg);
187 return FAIL;
188 }
189else
059ec3d9 190 {
7199e1ee 191 uschar *conn_info = smtp_get_connection_info();
5ca6d115 192 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
7199e1ee 193 conn_info += 5;
c562fd30 194 /* I'd like to get separated H= here, but too hard for now */
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195 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
196 conn_info, prefix, msg);
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197 return DEFER;
198 }
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199}
200
201
202
203/*************************************************
204* Callback to generate RSA key *
205*************************************************/
206
207/*
208Arguments:
209 s SSL connection
210 export not used
211 keylength keylength
212
213Returns: pointer to generated key
214*/
215
216static RSA *
217rsa_callback(SSL *s, int export, int keylength)
218{
219RSA *rsa_key;
220export = export; /* Shut picky compilers up */
221DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
222rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
223if (rsa_key == NULL)
224 {
225 ERR_error_string(ERR_get_error(), ssl_errstring);
226 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
227 ssl_errstring);
228 return NULL;
229 }
230return rsa_key;
231}
232
233
234
f5d78688 235/* Extreme debug
f2de3a33 236#ifndef DISABLE_OCSP
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237void
238x509_store_dump_cert_s_names(X509_STORE * store)
239{
240STACK_OF(X509_OBJECT) * roots= store->objs;
241int i;
242static uschar name[256];
243
244for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
245 {
246 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
247 if(tmp_obj->type == X509_LU_X509)
248 {
249 X509 * current_cert= tmp_obj->data.x509;
250 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
251 debug_printf(" %s\n", name);
252 }
253 }
254}
255#endif
256*/
257
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258
259/*************************************************
260* Callback for verification *
261*************************************************/
262
263/* The SSL library does certificate verification if set up to do so. This
264callback has the current yes/no state is in "state". If verification succeeded,
265we set up the tls_peerdn string. If verification failed, what happens depends
266on whether the client is required to present a verifiable certificate or not.
267
268If verification is optional, we change the state to yes, but still log the
269verification error. For some reason (it really would help to have proper
270documentation of OpenSSL), this callback function then gets called again, this
271time with state = 1. In fact, that's useful, because we can set up the peerdn
272value, but we must take care not to set the private verified flag on the second
273time through.
274
275Note: this function is not called if the client fails to present a certificate
276when asked. We get here only if a certificate has been received. Handling of
277optional verification for this case is done when requesting SSL to verify, by
278setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
279
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280May be called multiple times for different issues with a certificate, even
281for a given "depth" in the certificate chain.
282
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283Arguments:
284 state current yes/no state as 1/0
285 x509ctx certificate information.
a2ff477a 286 client TRUE for client startup, FALSE for server startup
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287
288Returns: 1 if verified, 0 if not
289*/
290
291static int
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292verify_callback(int state, X509_STORE_CTX *x509ctx,
293 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
059ec3d9 294{
421aff85 295X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
a7538db1 296int depth = X509_STORE_CTX_get_error_depth(x509ctx);
723fe533 297uschar * ev;
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298static uschar txt[256];
299
e51c7be2 300X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
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301
302if (state == 0)
303 {
304 log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s",
a7538db1 305 depth,
421aff85 306 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)),
059ec3d9 307 txt);
a2ff477a 308 *calledp = TRUE;
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309 if (!*optionalp)
310 {
421aff85 311 tlsp->peercert = X509_dup(cert);
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312 return 0; /* reject */
313 }
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314 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
315 "tls_try_verify_hosts)\n");
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316 }
317
a7538db1 318else if (depth != 0)
059ec3d9 319 {
a7538db1 320 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, txt);
f2de3a33 321#ifndef DISABLE_OCSP
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322 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
323 { /* client, wanting stapling */
324 /* Add the server cert's signing chain as the one
325 for the verification of the OCSP stapled information. */
326
327 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
421aff85 328 cert))
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329 ERR_clear_error();
330 }
331#endif
774ef2d7 332#ifdef EXPERIMENTAL_EVENT
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333 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
334 if (ev)
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335 {
336 tlsp->peercert = X509_dup(cert);
723fe533 337 if (event_raise(ev, US"tls:cert", string_sprintf("%d", depth)) == DEFER)
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338 {
339 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
340 "depth=%d cert=%s", depth, txt);
a7538db1 341 *calledp = TRUE;
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342 if (!*optionalp)
343 return 0; /* reject */
344 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
345 "(host in tls_try_verify_hosts)\n");
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346 }
347 X509_free(tlsp->peercert);
348 tlsp->peercert = NULL;
349 }
350#endif
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351 }
352else
353 {
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354#ifdef EXPERIMENTAL_CERTNAMES
355 uschar * verify_cert_hostnames;
356#endif
357
a2ff477a 358 tlsp->peerdn = txt;
421aff85 359 tlsp->peercert = X509_dup(cert);
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360
361#ifdef EXPERIMENTAL_CERTNAMES
362 if ( tlsp == &tls_out
363 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
364 /* client, wanting hostname check */
365
2dfb468b 366# if EXIM_HAVE_OPENSSL_CHECKHOST
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367# ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
368# define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
369# endif
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370 {
371 int sep = 0;
372 uschar * list = verify_cert_hostnames;
373 uschar * name;
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374 int rc;
375 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
376 if ((rc = X509_check_host(cert, name, 0,
377 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS)))
378 {
379 if (rc < 0)
380 {
381 log_write(0, LOG_MAIN, "SSL verify error: internal error\n");
382 name = NULL;
383 }
e51c7be2 384 break;
d8e7834a 385 }
e51c7be2
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386 if (!name)
387 {
388 log_write(0, LOG_MAIN,
389 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
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390 *calledp = TRUE;
391 if (!*optionalp)
392 return 0; /* reject */
393 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
394 "tls_try_verify_hosts)\n");
e51c7be2
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395 }
396 }
397# else
398 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
399 {
400 log_write(0, LOG_MAIN,
401 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
a3ef7310
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402 *calledp = TRUE;
403 if (!*optionalp)
404 return 0; /* reject */
405 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
406 "tls_try_verify_hosts)\n");
e51c7be2
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407 }
408# endif
e5cccda9 409#endif /*EXPERIMENTAL_CERTNAMES*/
e51c7be2 410
774ef2d7 411#ifdef EXPERIMENTAL_EVENT
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412 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
413 if (ev)
414 if (event_raise(ev, US"tls:cert", US"0") == DEFER)
a7538db1
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415 {
416 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
417 "depth=0 cert=%s", txt);
a7538db1 418 *calledp = TRUE;
a3ef7310
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419 if (!*optionalp)
420 return 0; /* reject */
421 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
422 "(host in tls_try_verify_hosts)\n");
a7538db1 423 }
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424#endif
425
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426 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
427 *calledp ? "" : " authenticated", txt);
428 if (!*calledp) tlsp->certificate_verified = TRUE;
429 *calledp = TRUE;
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430 }
431
a7538db1 432return 1; /* accept, at least for this level */
059ec3d9
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433}
434
a2ff477a
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435static int
436verify_callback_client(int state, X509_STORE_CTX *x509ctx)
437{
f5d78688 438return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
a2ff477a
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439}
440
441static int
442verify_callback_server(int state, X509_STORE_CTX *x509ctx)
443{
f5d78688 444return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
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445}
446
059ec3d9 447
e5cccda9 448#ifdef EXPERIMENTAL_DANE
53a7196b 449
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450/* This gets called *by* the dane library verify callback, which interposes
451itself.
452*/
453static int
454verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
455{
456X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
457static uschar txt[256];
774ef2d7 458#ifdef EXPERIMENTAL_EVENT
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459int depth = X509_STORE_CTX_get_error_depth(x509ctx);
460#endif
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461
462X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
463
464DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", txt);
465tls_out.peerdn = txt;
466tls_out.peercert = X509_dup(cert);
467
774ef2d7 468#ifdef EXPERIMENTAL_EVENT
83b27293
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469 if (client_static_cbinfo->event_action)
470 {
774ef2d7 471 if (event_raise(client_static_cbinfo->event_action,
83b27293
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472 US"tls:cert", string_sprintf("%d", depth)) == DEFER)
473 {
474 log_write(0, LOG_MAIN, "DANE verify denied by event-action: "
475 "depth=%d cert=%s", depth, txt);
476 tls_out.certificate_verified = FALSE;
477 return 0; /* reject */
478 }
479 if (depth != 0)
480 {
481 X509_free(tls_out.peercert);
482 tls_out.peercert = NULL;
483 }
484 }
485#endif
486
e5cccda9 487if (state == 1)
53a7196b 488 tls_out.dane_verified =
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489 tls_out.certificate_verified = TRUE;
490return 1;
491}
53a7196b
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492
493#endif /*EXPERIMENTAL_DANE*/
e5cccda9 494
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495
496/*************************************************
497* Information callback *
498*************************************************/
499
500/* The SSL library functions call this from time to time to indicate what they
7be682ca
PP
501are doing. We copy the string to the debugging output when TLS debugging has
502been requested.
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503
504Arguments:
505 s the SSL connection
506 where
507 ret
508
509Returns: nothing
510*/
511
512static void
513info_callback(SSL *s, int where, int ret)
514{
515where = where;
516ret = ret;
517DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
518}
519
520
521
522/*************************************************
523* Initialize for DH *
524*************************************************/
525
526/* If dhparam is set, expand it, and load up the parameters for DH encryption.
527
528Arguments:
a799883d 529 dhparam DH parameter file or fixed parameter identity string
7199e1ee 530 host connected host, if client; NULL if server
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531
532Returns: TRUE if OK (nothing to set up, or setup worked)
533*/
534
535static BOOL
a799883d 536init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host)
059ec3d9 537{
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538BIO *bio;
539DH *dh;
540uschar *dhexpanded;
a799883d 541const char *pem;
059ec3d9
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542
543if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
544 return FALSE;
545
0df4ab80 546if (!dhexpanded || !*dhexpanded)
a799883d 547 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
a799883d 548else if (dhexpanded[0] == '/')
059ec3d9 549 {
0df4ab80 550 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
059ec3d9 551 {
7199e1ee 552 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
a799883d
PP
553 host, US strerror(errno));
554 return FALSE;
059ec3d9 555 }
a799883d
PP
556 }
557else
558 {
559 if (Ustrcmp(dhexpanded, "none") == 0)
059ec3d9 560 {
a799883d
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561 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
562 return TRUE;
059ec3d9 563 }
a799883d 564
0df4ab80 565 if (!(pem = std_dh_prime_named(dhexpanded)))
a799883d
PP
566 {
567 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
568 host, US strerror(errno));
569 return FALSE;
570 }
571 bio = BIO_new_mem_buf(CS pem, -1);
572 }
573
0df4ab80 574if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
a799883d 575 {
059ec3d9 576 BIO_free(bio);
a799883d
PP
577 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
578 host, NULL);
579 return FALSE;
580 }
581
582/* Even if it is larger, we silently return success rather than cause things
583 * to fail out, so that a too-large DH will not knock out all TLS; it's a
584 * debatable choice. */
585if ((8*DH_size(dh)) > tls_dh_max_bits)
586 {
587 DEBUG(D_tls)
588 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
589 8*DH_size(dh), tls_dh_max_bits);
590 }
591else
592 {
593 SSL_CTX_set_tmp_dh(sctx, dh);
594 DEBUG(D_tls)
595 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
596 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
059ec3d9
PH
597 }
598
a799883d
PP
599DH_free(dh);
600BIO_free(bio);
601
602return TRUE;
059ec3d9
PH
603}
604
605
606
607
f2de3a33 608#ifndef DISABLE_OCSP
3f7eeb86
PP
609/*************************************************
610* Load OCSP information into state *
611*************************************************/
612
f5d78688 613/* Called to load the server OCSP response from the given file into memory, once
3f7eeb86
PP
614caller has determined this is needed. Checks validity. Debugs a message
615if invalid.
616
617ASSUMES: single response, for single cert.
618
619Arguments:
620 sctx the SSL_CTX* to update
621 cbinfo various parts of session state
622 expanded the filename putatively holding an OCSP response
623
624*/
625
626static void
f5d78688 627ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
3f7eeb86
PP
628{
629BIO *bio;
630OCSP_RESPONSE *resp;
631OCSP_BASICRESP *basic_response;
632OCSP_SINGLERESP *single_response;
633ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
634X509_STORE *store;
635unsigned long verify_flags;
636int status, reason, i;
637
f5d78688
JH
638cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
639if (cbinfo->u_ocsp.server.response)
3f7eeb86 640 {
f5d78688
JH
641 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
642 cbinfo->u_ocsp.server.response = NULL;
3f7eeb86
PP
643 }
644
f5d78688 645bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
3f7eeb86
PP
646if (!bio)
647 {
648 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
f5d78688 649 cbinfo->u_ocsp.server.file_expanded);
3f7eeb86
PP
650 return;
651 }
652
653resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
654BIO_free(bio);
655if (!resp)
656 {
657 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
658 return;
659 }
660
661status = OCSP_response_status(resp);
662if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
663 {
664 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
665 OCSP_response_status_str(status), status);
f5d78688 666 goto bad;
3f7eeb86
PP
667 }
668
669basic_response = OCSP_response_get1_basic(resp);
670if (!basic_response)
671 {
672 DEBUG(D_tls)
673 debug_printf("OCSP response parse error: unable to extract basic response.\n");
f5d78688 674 goto bad;
3f7eeb86
PP
675 }
676
677store = SSL_CTX_get_cert_store(sctx);
678verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
679
680/* May need to expose ability to adjust those flags?
681OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
682OCSP_TRUSTOTHER OCSP_NOINTERN */
683
684i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
685if (i <= 0)
686 {
687 DEBUG(D_tls) {
688 ERR_error_string(ERR_get_error(), ssl_errstring);
689 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
f5d78688
JH
690 }
691 goto bad;
3f7eeb86
PP
692 }
693
694/* Here's the simplifying assumption: there's only one response, for the
695one certificate we use, and nothing for anything else in a chain. If this
696proves false, we need to extract a cert id from our issued cert
697(tls_certificate) and use that for OCSP_resp_find_status() (which finds the
698right cert in the stack and then calls OCSP_single_get0_status()).
699
700I'm hoping to avoid reworking a bunch more of how we handle state here. */
701single_response = OCSP_resp_get0(basic_response, 0);
702if (!single_response)
703 {
704 DEBUG(D_tls)
705 debug_printf("Unable to get first response from OCSP basic response.\n");
f5d78688 706 goto bad;
3f7eeb86
PP
707 }
708
709status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
f5d78688 710if (status != V_OCSP_CERTSTATUS_GOOD)
3f7eeb86 711 {
f5d78688
JH
712 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
713 OCSP_cert_status_str(status), status,
714 OCSP_crl_reason_str(reason), reason);
715 goto bad;
3f7eeb86
PP
716 }
717
718if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
719 {
720 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
f5d78688 721 goto bad;
3f7eeb86
PP
722 }
723
f5d78688 724supply_response:
018058b2 725 cbinfo->u_ocsp.server.response = resp;
f5d78688
JH
726return;
727
728bad:
018058b2
JH
729 if (running_in_test_harness)
730 {
731 extern char ** environ;
732 uschar ** p;
733 for (p = USS environ; *p != NULL; p++)
734 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
735 {
736 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
737 goto supply_response;
738 }
739 }
f5d78688 740return;
3f7eeb86 741}
f2de3a33 742#endif /*!DISABLE_OCSP*/
3f7eeb86
PP
743
744
745
746
059ec3d9 747/*************************************************
7be682ca
PP
748* Expand key and cert file specs *
749*************************************************/
750
f5d78688 751/* Called once during tls_init and possibly again during TLS setup, for a
7be682ca
PP
752new context, if Server Name Indication was used and tls_sni was seen in
753the certificate string.
754
755Arguments:
756 sctx the SSL_CTX* to update
757 cbinfo various parts of session state
758
759Returns: OK/DEFER/FAIL
760*/
761
762static int
3f7eeb86 763tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
7be682ca
PP
764{
765uschar *expanded;
766
767if (cbinfo->certificate == NULL)
768 return OK;
769
d9b2312b
JH
770if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
771 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
772 Ustrstr(cbinfo->certificate, US"tls_out_sni")
773 )
7be682ca
PP
774 reexpand_tls_files_for_sni = TRUE;
775
776if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
777 return DEFER;
778
779if (expanded != NULL)
780 {
781 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
782 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
783 return tls_error(string_sprintf(
784 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
785 cbinfo->host, NULL);
786 }
787
788if (cbinfo->privatekey != NULL &&
789 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
790 return DEFER;
791
792/* If expansion was forced to fail, key_expanded will be NULL. If the result
793of the expansion is an empty string, ignore it also, and assume the private
794key is in the same file as the certificate. */
795
796if (expanded != NULL && *expanded != 0)
797 {
798 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
799 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
800 return tls_error(string_sprintf(
801 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
802 }
803
f2de3a33 804#ifndef DISABLE_OCSP
f5d78688 805if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
3f7eeb86 806 {
f5d78688 807 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
3f7eeb86
PP
808 return DEFER;
809
810 if (expanded != NULL && *expanded != 0)
811 {
812 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
f5d78688
JH
813 if (cbinfo->u_ocsp.server.file_expanded &&
814 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
3f7eeb86
PP
815 {
816 DEBUG(D_tls)
817 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
818 } else {
819 ocsp_load_response(sctx, cbinfo, expanded);
820 }
821 }
822 }
823#endif
824
7be682ca
PP
825return OK;
826}
827
828
829
830
831/*************************************************
832* Callback to handle SNI *
833*************************************************/
834
835/* Called when acting as server during the TLS session setup if a Server Name
836Indication extension was sent by the client.
837
838API documentation is OpenSSL s_server.c implementation.
839
840Arguments:
841 s SSL* of the current session
842 ad unknown (part of OpenSSL API) (unused)
843 arg Callback of "our" registered data
844
845Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
846*/
847
3bcbbbe2 848#ifdef EXIM_HAVE_OPENSSL_TLSEXT
7be682ca 849static int
7be682ca
PP
850tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
851{
852const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
3f7eeb86 853tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
7be682ca 854int rc;
3f0945ff 855int old_pool = store_pool;
7be682ca
PP
856
857if (!servername)
858 return SSL_TLSEXT_ERR_OK;
859
3f0945ff 860DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
7be682ca
PP
861 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
862
863/* Make the extension value available for expansion */
3f0945ff 864store_pool = POOL_PERM;
817d9f57 865tls_in.sni = string_copy(US servername);
3f0945ff 866store_pool = old_pool;
7be682ca
PP
867
868if (!reexpand_tls_files_for_sni)
869 return SSL_TLSEXT_ERR_OK;
870
871/* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
872not confident that memcpy wouldn't break some internal reference counting.
873Especially since there's a references struct member, which would be off. */
874
0df4ab80 875if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
7be682ca
PP
876 {
877 ERR_error_string(ERR_get_error(), ssl_errstring);
878 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
879 return SSL_TLSEXT_ERR_NOACK;
880 }
881
882/* Not sure how many of these are actually needed, since SSL object
883already exists. Might even need this selfsame callback, for reneg? */
884
817d9f57
JH
885SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
886SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
887SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
888SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
889SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
890SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
7be682ca 891if (cbinfo->server_cipher_list)
817d9f57 892 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
f2de3a33 893#ifndef DISABLE_OCSP
f5d78688 894if (cbinfo->u_ocsp.server.file)
3f7eeb86 895 {
f5d78688 896 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
14c7b357 897 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
3f7eeb86
PP
898 }
899#endif
7be682ca 900
983207c1 901rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
7be682ca
PP
902if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
903
3f7eeb86
PP
904/* do this after setup_certs, because this can require the certs for verifying
905OCSP information. */
817d9f57 906rc = tls_expand_session_files(server_sni, cbinfo);
7be682ca
PP
907if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
908
0df4ab80
JH
909if (!init_dh(server_sni, cbinfo->dhparam, NULL))
910 return SSL_TLSEXT_ERR_NOACK;
a799883d 911
7be682ca 912DEBUG(D_tls) debug_printf("Switching SSL context.\n");
817d9f57 913SSL_set_SSL_CTX(s, server_sni);
7be682ca
PP
914
915return SSL_TLSEXT_ERR_OK;
916}
3bcbbbe2 917#endif /* EXIM_HAVE_OPENSSL_TLSEXT */
7be682ca
PP
918
919
920
921
f2de3a33 922#ifndef DISABLE_OCSP
f5d78688 923
3f7eeb86
PP
924/*************************************************
925* Callback to handle OCSP Stapling *
926*************************************************/
927
928/* Called when acting as server during the TLS session setup if the client
929requests OCSP information with a Certificate Status Request.
930
931Documentation via openssl s_server.c and the Apache patch from the OpenSSL
932project.
933
934*/
935
936static int
f5d78688 937tls_server_stapling_cb(SSL *s, void *arg)
3f7eeb86
PP
938{
939const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
940uschar *response_der;
941int response_der_len;
942
af4a1bca
JH
943DEBUG(D_tls)
944 debug_printf("Received TLS status request (OCSP stapling); %s response.",
f5d78688
JH
945 cbinfo->u_ocsp.server.response ? "have" : "lack");
946
44662487 947tls_in.ocsp = OCSP_NOT_RESP;
f5d78688 948if (!cbinfo->u_ocsp.server.response)
3f7eeb86
PP
949 return SSL_TLSEXT_ERR_NOACK;
950
951response_der = NULL;
44662487
JH
952response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
953 &response_der);
3f7eeb86
PP
954if (response_der_len <= 0)
955 return SSL_TLSEXT_ERR_NOACK;
956
5e55c7a9 957SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
44662487 958tls_in.ocsp = OCSP_VFIED;
3f7eeb86
PP
959return SSL_TLSEXT_ERR_OK;
960}
961
3f7eeb86 962
f5d78688
JH
963static void
964time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
965{
966BIO_printf(bp, "\t%s: ", str);
967ASN1_GENERALIZEDTIME_print(bp, time);
968BIO_puts(bp, "\n");
969}
970
971static int
972tls_client_stapling_cb(SSL *s, void *arg)
973{
974tls_ext_ctx_cb * cbinfo = arg;
975const unsigned char * p;
976int len;
977OCSP_RESPONSE * rsp;
978OCSP_BASICRESP * bs;
979int i;
980
981DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
982len = SSL_get_tlsext_status_ocsp_resp(s, &p);
983if(!p)
984 {
44662487
JH
985 /* Expect this when we requested ocsp but got none */
986 if ( cbinfo->u_ocsp.client.verify_required
987 && log_extra_selector & LX_tls_cipher)
988 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
f5d78688
JH
989 else
990 DEBUG(D_tls) debug_printf(" null\n");
44662487 991 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
f5d78688 992 }
018058b2 993
f5d78688
JH
994if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
995 {
018058b2 996 tls_out.ocsp = OCSP_FAILED;
f5d78688 997 if (log_extra_selector & LX_tls_cipher)
1eca31ca 998 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
f5d78688
JH
999 else
1000 DEBUG(D_tls) debug_printf(" parse error\n");
1001 return 0;
1002 }
1003
1004if(!(bs = OCSP_response_get1_basic(rsp)))
1005 {
018058b2 1006 tls_out.ocsp = OCSP_FAILED;
f5d78688 1007 if (log_extra_selector & LX_tls_cipher)
1eca31ca 1008 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
f5d78688
JH
1009 else
1010 DEBUG(D_tls) debug_printf(" error parsing response\n");
1011 OCSP_RESPONSE_free(rsp);
1012 return 0;
1013 }
1014
1015/* We'd check the nonce here if we'd put one in the request. */
1016/* However that would defeat cacheability on the server so we don't. */
1017
f5d78688
JH
1018/* This section of code reworked from OpenSSL apps source;
1019 The OpenSSL Project retains copyright:
1020 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1021*/
1022 {
1023 BIO * bp = NULL;
f5d78688
JH
1024 int status, reason;
1025 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1026
1027 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
1028
1029 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1030
1031 /* Use the chain that verified the server cert to verify the stapled info */
1032 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1033
44662487
JH
1034 if ((i = OCSP_basic_verify(bs, NULL,
1035 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
f5d78688 1036 {
018058b2 1037 tls_out.ocsp = OCSP_FAILED;
1eca31ca
JH
1038 if (log_extra_selector & LX_tls_cipher)
1039 log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable");
f5d78688
JH
1040 BIO_printf(bp, "OCSP response verify failure\n");
1041 ERR_print_errors(bp);
44662487 1042 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
f5d78688
JH
1043 goto out;
1044 }
1045
1046 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1047
1048 {
1049 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1050 OCSP_SINGLERESP * single;
1051
1052 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1053 {
018058b2 1054 tls_out.ocsp = OCSP_FAILED;
44662487
JH
1055 log_write(0, LOG_MAIN, "OCSP stapling "
1056 "with multiple responses not handled");
1057 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
f5d78688
JH
1058 goto out;
1059 }
1060 single = OCSP_resp_get0(bs, 0);
44662487
JH
1061 status = OCSP_single_get0_status(single, &reason, &rev,
1062 &thisupd, &nextupd);
f5d78688
JH
1063 }
1064
f5d78688
JH
1065 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1066 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
44662487
JH
1067 if (!OCSP_check_validity(thisupd, nextupd,
1068 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
f5d78688 1069 {
018058b2 1070 tls_out.ocsp = OCSP_FAILED;
f5d78688
JH
1071 DEBUG(D_tls) ERR_print_errors(bp);
1072 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
44662487 1073 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
f5d78688 1074 }
44662487 1075 else
f5d78688 1076 {
44662487
JH
1077 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1078 OCSP_cert_status_str(status));
1079 switch(status)
1080 {
1081 case V_OCSP_CERTSTATUS_GOOD:
44662487 1082 tls_out.ocsp = OCSP_VFIED;
018058b2 1083 i = 1;
44662487
JH
1084 break;
1085 case V_OCSP_CERTSTATUS_REVOKED:
018058b2 1086 tls_out.ocsp = OCSP_FAILED;
44662487
JH
1087 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1088 reason != -1 ? "; reason: " : "",
1089 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1090 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1091 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1092 break;
1093 default:
018058b2 1094 tls_out.ocsp = OCSP_FAILED;
44662487
JH
1095 log_write(0, LOG_MAIN,
1096 "Server certificate status unknown, in OCSP stapling");
1097 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1098 break;
1099 }
f5d78688
JH
1100 }
1101 out:
1102 BIO_free(bp);
1103 }
1104
1105OCSP_RESPONSE_free(rsp);
1106return i;
1107}
f2de3a33 1108#endif /*!DISABLE_OCSP*/
3f7eeb86
PP
1109
1110
7be682ca 1111/*************************************************
059ec3d9
PH
1112* Initialize for TLS *
1113*************************************************/
1114
e51c7be2
JH
1115/* Called from both server and client code, to do preliminary initialization
1116of the library. We allocate and return a context structure.
059ec3d9
PH
1117
1118Arguments:
946ecbe0 1119 ctxp returned SSL context
059ec3d9
PH
1120 host connected host, if client; NULL if server
1121 dhparam DH parameter file
1122 certificate certificate file
1123 privatekey private key
f5d78688 1124 ocsp_file file of stapling info (server); flag for require ocsp (client)
059ec3d9 1125 addr address if client; NULL if server (for some randomness)
946ecbe0 1126 cbp place to put allocated callback context
059ec3d9
PH
1127
1128Returns: OK/DEFER/FAIL
1129*/
1130
1131static int
817d9f57 1132tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
3f7eeb86 1133 uschar *privatekey,
f2de3a33 1134#ifndef DISABLE_OCSP
3f7eeb86
PP
1135 uschar *ocsp_file,
1136#endif
817d9f57 1137 address_item *addr, tls_ext_ctx_cb ** cbp)
059ec3d9 1138{
77bb000f 1139long init_options;
7be682ca 1140int rc;
77bb000f 1141BOOL okay;
a7538db1 1142tls_ext_ctx_cb * cbinfo;
7be682ca
PP
1143
1144cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1145cbinfo->certificate = certificate;
1146cbinfo->privatekey = privatekey;
f2de3a33 1147#ifndef DISABLE_OCSP
f5d78688
JH
1148if ((cbinfo->is_server = host==NULL))
1149 {
1150 cbinfo->u_ocsp.server.file = ocsp_file;
1151 cbinfo->u_ocsp.server.file_expanded = NULL;
1152 cbinfo->u_ocsp.server.response = NULL;
1153 }
1154else
1155 cbinfo->u_ocsp.client.verify_store = NULL;
3f7eeb86 1156#endif
7be682ca 1157cbinfo->dhparam = dhparam;
0df4ab80 1158cbinfo->server_cipher_list = NULL;
7be682ca 1159cbinfo->host = host;
774ef2d7 1160#ifdef EXPERIMENTAL_EVENT
a7538db1
JH
1161cbinfo->event_action = NULL;
1162#endif
77bb000f 1163
059ec3d9
PH
1164SSL_load_error_strings(); /* basic set up */
1165OpenSSL_add_ssl_algorithms();
1166
388d6564 1167#if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
77bb000f 1168/* SHA256 is becoming ever more popular. This makes sure it gets added to the
a0475b69
TK
1169list of available digests. */
1170EVP_add_digest(EVP_sha256());
cf1ef1a9 1171#endif
a0475b69 1172
f0f5a555
PP
1173/* Create a context.
1174The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1175negotiation in the different methods; as far as I can tell, the only
1176*_{server,client}_method which allows negotiation is SSLv23, which exists even
1177when OpenSSL is built without SSLv2 support.
1178By disabling with openssl_options, we can let admins re-enable with the
1179existing knob. */
059ec3d9 1180
817d9f57 1181*ctxp = SSL_CTX_new((host == NULL)?
059ec3d9
PH
1182 SSLv23_server_method() : SSLv23_client_method());
1183
817d9f57 1184if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
059ec3d9
PH
1185
1186/* It turns out that we need to seed the random number generator this early in
1187order to get the full complement of ciphers to work. It took me roughly a day
1188of work to discover this by experiment.
1189
1190On systems that have /dev/urandom, SSL may automatically seed itself from
1191there. Otherwise, we have to make something up as best we can. Double check
1192afterwards. */
1193
1194if (!RAND_status())
1195 {
1196 randstuff r;
9e3331ea 1197 gettimeofday(&r.tv, NULL);
059ec3d9
PH
1198 r.p = getpid();
1199
1200 RAND_seed((uschar *)(&r), sizeof(r));
1201 RAND_seed((uschar *)big_buffer, big_buffer_size);
1202 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1203
1204 if (!RAND_status())
7199e1ee 1205 return tls_error(US"RAND_status", host,
5ca6d115 1206 US"unable to seed random number generator");
059ec3d9
PH
1207 }
1208
1209/* Set up the information callback, which outputs if debugging is at a suitable
1210level. */
1211
817d9f57 1212SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
059ec3d9 1213
c80c5570 1214/* Automatically re-try reads/writes after renegotiation. */
817d9f57 1215(void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
c80c5570 1216
77bb000f
PP
1217/* Apply administrator-supplied work-arounds.
1218Historically we applied just one requested option,
1219SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1220moved to an administrator-controlled list of options to specify and
1221grandfathered in the first one as the default value for "openssl_options".
059ec3d9 1222
77bb000f
PP
1223No OpenSSL version number checks: the options we accept depend upon the
1224availability of the option value macros from OpenSSL. */
059ec3d9 1225
77bb000f
PP
1226okay = tls_openssl_options_parse(openssl_options, &init_options);
1227if (!okay)
73a46702 1228 return tls_error(US"openssl_options parsing failed", host, NULL);
77bb000f
PP
1229
1230if (init_options)
1231 {
1232 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
817d9f57 1233 if (!(SSL_CTX_set_options(*ctxp, init_options)))
77bb000f
PP
1234 return tls_error(string_sprintf(
1235 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1236 }
1237else
1238 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
059ec3d9
PH
1239
1240/* Initialize with DH parameters if supplied */
1241
817d9f57 1242if (!init_dh(*ctxp, dhparam, host)) return DEFER;
059ec3d9 1243
3f7eeb86 1244/* Set up certificate and key (and perhaps OCSP info) */
059ec3d9 1245
817d9f57 1246rc = tls_expand_session_files(*ctxp, cbinfo);
7be682ca 1247if (rc != OK) return rc;
c91535f3 1248
7be682ca 1249/* If we need to handle SNI, do so */
3bcbbbe2 1250#ifdef EXIM_HAVE_OPENSSL_TLSEXT
f5d78688 1251if (host == NULL) /* server */
3f0945ff 1252 {
f2de3a33 1253# ifndef DISABLE_OCSP
f5d78688 1254 /* We check u_ocsp.server.file, not server.response, because we care about if
3f7eeb86
PP
1255 the option exists, not what the current expansion might be, as SNI might
1256 change the certificate and OCSP file in use between now and the time the
1257 callback is invoked. */
f5d78688 1258 if (cbinfo->u_ocsp.server.file)
3f7eeb86 1259 {
f5d78688 1260 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
5e55c7a9 1261 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
3f7eeb86 1262 }
f5d78688 1263# endif
3f0945ff
PP
1264 /* We always do this, so that $tls_sni is available even if not used in
1265 tls_certificate */
817d9f57
JH
1266 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1267 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
3f0945ff 1268 }
f2de3a33 1269# ifndef DISABLE_OCSP
f5d78688
JH
1270else /* client */
1271 if(ocsp_file) /* wanting stapling */
1272 {
1273 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1274 {
1275 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1276 return FAIL;
1277 }
1278 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1279 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1280 }
1281# endif
7be682ca 1282#endif
059ec3d9 1283
e51c7be2
JH
1284#ifdef EXPERIMENTAL_CERTNAMES
1285cbinfo->verify_cert_hostnames = NULL;
1286#endif
1287
059ec3d9
PH
1288/* Set up the RSA callback */
1289
817d9f57 1290SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
059ec3d9
PH
1291
1292/* Finally, set the timeout, and we are done */
1293
817d9f57 1294SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
059ec3d9 1295DEBUG(D_tls) debug_printf("Initialized TLS\n");
7be682ca 1296
817d9f57 1297*cbp = cbinfo;
7be682ca 1298
059ec3d9
PH
1299return OK;
1300}
1301
1302
1303
1304
1305/*************************************************
1306* Get name of cipher in use *
1307*************************************************/
1308
817d9f57 1309/*
059ec3d9 1310Argument: pointer to an SSL structure for the connection
817d9f57
JH
1311 buffer to use for answer
1312 size of buffer
1313 pointer to number of bits for cipher
059ec3d9
PH
1314Returns: nothing
1315*/
1316
1317static void
817d9f57 1318construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
059ec3d9 1319{
57b3a7f5
PP
1320/* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1321yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1322the accessor functions use const in the prototype. */
1323const SSL_CIPHER *c;
d9784128 1324const uschar *ver;
059ec3d9 1325
d9784128 1326ver = (const uschar *)SSL_get_version(ssl);
059ec3d9 1327
57b3a7f5 1328c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
817d9f57 1329SSL_CIPHER_get_bits(c, bits);
059ec3d9 1330
817d9f57
JH
1331string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1332 SSL_CIPHER_get_name(c), *bits);
059ec3d9
PH
1333
1334DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1335}
1336
1337
1338
1339
1340
1341/*************************************************
1342* Set up for verifying certificates *
1343*************************************************/
1344
1345/* Called by both client and server startup
1346
1347Arguments:
7be682ca 1348 sctx SSL_CTX* to initialise
059ec3d9
PH
1349 certs certs file or NULL
1350 crl CRL file or NULL
1351 host NULL in a server; the remote host in a client
1352 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1353 otherwise passed as FALSE
983207c1 1354 cert_vfy_cb Callback function for certificate verification
059ec3d9
PH
1355
1356Returns: OK/DEFER/FAIL
1357*/
1358
1359static int
983207c1
JH
1360setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1361 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
059ec3d9
PH
1362{
1363uschar *expcerts, *expcrl;
1364
1365if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1366 return DEFER;
1367
26e72755 1368if (expcerts != NULL && *expcerts != '\0')
059ec3d9
PH
1369 {
1370 struct stat statbuf;
7be682ca 1371 if (!SSL_CTX_set_default_verify_paths(sctx))
7199e1ee 1372 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
059ec3d9
PH
1373
1374 if (Ustat(expcerts, &statbuf) < 0)
1375 {
1376 log_write(0, LOG_MAIN|LOG_PANIC,
1377 "failed to stat %s for certificates", expcerts);
1378 return DEFER;
1379 }
1380 else
1381 {
1382 uschar *file, *dir;
1383 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1384 { file = NULL; dir = expcerts; }
1385 else
1386 { file = expcerts; dir = NULL; }
1387
1388 /* If a certificate file is empty, the next function fails with an
1389 unhelpful error message. If we skip it, we get the correct behaviour (no
1390 certificates are recognized, but the error message is still misleading (it
1391 says no certificate was supplied.) But this is better. */
1392
1393 if ((file == NULL || statbuf.st_size > 0) &&
7be682ca 1394 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
7199e1ee 1395 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
059ec3d9 1396
3281c6ea 1397 /* Load the list of CAs for which we will accept certs, for sending
a805c12a
JH
1398 to the client. This is only for the one-file tls_verify_certificates
1399 variant.
1400 If a list isn't loaded into the server, but
1401 some verify locations are set, the server end appears to make
1402 a wildcard reqest for client certs.
1403 Meanwhile, the client library as deafult behaviour *ignores* the list
1404 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1405 Because of this, and that the dir variant is likely only used for
1406 the public-CA bundle (not for a private CA), not worth fixing.
1407 */
059ec3d9
PH
1408 if (file != NULL)
1409 {
3281c6ea
JH
1410 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
1411DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1412 sk_X509_NAME_num(names));
1413 SSL_CTX_set_client_CA_list(sctx, names);
059ec3d9
PH
1414 }
1415 }
1416
1417 /* Handle a certificate revocation list. */
1418
1419 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1420
8b417f2c
PH
1421 /* This bit of code is now the version supplied by Lars Mainka. (I have
1422 * merely reformatted it into the Exim code style.)
1423
1424 * "From here I changed the code to add support for multiple crl's
1425 * in pem format in one file or to support hashed directory entries in
1426 * pem format instead of a file. This method now uses the library function
1427 * X509_STORE_load_locations to add the CRL location to the SSL context.
1428 * OpenSSL will then handle the verify against CA certs and CRLs by
1429 * itself in the verify callback." */
1430
059ec3d9
PH
1431 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1432 if (expcrl != NULL && *expcrl != 0)
1433 {
8b417f2c
PH
1434 struct stat statbufcrl;
1435 if (Ustat(expcrl, &statbufcrl) < 0)
1436 {
1437 log_write(0, LOG_MAIN|LOG_PANIC,
1438 "failed to stat %s for certificates revocation lists", expcrl);
1439 return DEFER;
1440 }
1441 else
059ec3d9 1442 {
8b417f2c
PH
1443 /* is it a file or directory? */
1444 uschar *file, *dir;
7be682ca 1445 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
8b417f2c 1446 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
059ec3d9 1447 {
8b417f2c
PH
1448 file = NULL;
1449 dir = expcrl;
1450 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
059ec3d9
PH
1451 }
1452 else
1453 {
8b417f2c
PH
1454 file = expcrl;
1455 dir = NULL;
1456 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
059ec3d9 1457 }
8b417f2c 1458 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
7199e1ee 1459 return tls_error(US"X509_STORE_load_locations", host, NULL);
8b417f2c
PH
1460
1461 /* setting the flags to check against the complete crl chain */
1462
1463 X509_STORE_set_flags(cvstore,
1464 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
059ec3d9 1465 }
059ec3d9
PH
1466 }
1467
1468 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1469
1470 /* If verification is optional, don't fail if no certificate */
1471
7be682ca 1472 SSL_CTX_set_verify(sctx,
059ec3d9 1473 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
983207c1 1474 cert_vfy_cb);
059ec3d9
PH
1475 }
1476
1477return OK;
1478}
1479
1480
1481
1482/*************************************************
1483* Start a TLS session in a server *
1484*************************************************/
1485
1486/* This is called when Exim is running as a server, after having received
1487the STARTTLS command. It must respond to that command, and then negotiate
1488a TLS session.
1489
1490Arguments:
1491 require_ciphers allowed ciphers
1492
1493Returns: OK on success
1494 DEFER for errors before the start of the negotiation
1495 FAIL for errors during the negotation; the server can't
1496 continue running.
1497*/
1498
1499int
17c76198 1500tls_server_start(const uschar *require_ciphers)
059ec3d9
PH
1501{
1502int rc;
1503uschar *expciphers;
7be682ca 1504tls_ext_ctx_cb *cbinfo;
817d9f57 1505static uschar cipherbuf[256];
059ec3d9
PH
1506
1507/* Check for previous activation */
1508
817d9f57 1509if (tls_in.active >= 0)
059ec3d9 1510 {
5ca6d115 1511 tls_error(US"STARTTLS received after TLS started", NULL, US"");
059ec3d9
PH
1512 smtp_printf("554 Already in TLS\r\n");
1513 return FAIL;
1514 }
1515
1516/* Initialize the SSL library. If it fails, it will already have logged
1517the error. */
1518
817d9f57 1519rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
f2de3a33 1520#ifndef DISABLE_OCSP
3f7eeb86
PP
1521 tls_ocsp_file,
1522#endif
817d9f57 1523 NULL, &server_static_cbinfo);
059ec3d9 1524if (rc != OK) return rc;
817d9f57 1525cbinfo = server_static_cbinfo;
059ec3d9
PH
1526
1527if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1528 return FAIL;
1529
1530/* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
17c76198
PP
1531were historically separated by underscores. So that I can use either form in my
1532tests, and also for general convenience, we turn underscores into hyphens here.
1533*/
059ec3d9
PH
1534
1535if (expciphers != NULL)
1536 {
1537 uschar *s = expciphers;
1538 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1539 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
817d9f57 1540 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
7199e1ee 1541 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
7be682ca 1542 cbinfo->server_cipher_list = expciphers;
059ec3d9
PH
1543 }
1544
1545/* If this is a host for which certificate verification is mandatory or
1546optional, set up appropriately. */
1547
817d9f57 1548tls_in.certificate_verified = FALSE;
53a7196b
JH
1549#ifdef EXPERIMENTAL_DANE
1550tls_in.dane_verified = FALSE;
1551#endif
a2ff477a 1552server_verify_callback_called = FALSE;
059ec3d9
PH
1553
1554if (verify_check_host(&tls_verify_hosts) == OK)
1555 {
983207c1
JH
1556 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1557 FALSE, verify_callback_server);
059ec3d9 1558 if (rc != OK) return rc;
a2ff477a 1559 server_verify_optional = FALSE;
059ec3d9
PH
1560 }
1561else if (verify_check_host(&tls_try_verify_hosts) == OK)
1562 {
983207c1
JH
1563 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1564 TRUE, verify_callback_server);
059ec3d9 1565 if (rc != OK) return rc;
a2ff477a 1566 server_verify_optional = TRUE;
059ec3d9
PH
1567 }
1568
1569/* Prepare for new connection */
1570
817d9f57 1571if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
da3ad30d
PP
1572
1573/* Warning: we used to SSL_clear(ssl) here, it was removed.
1574 *
1575 * With the SSL_clear(), we get strange interoperability bugs with
1576 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1577 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1578 *
1579 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1580 * session shutdown. In this case, we have a brand new object and there's no
1581 * obvious reason to immediately clear it. I'm guessing that this was
1582 * originally added because of incomplete initialisation which the clear fixed,
1583 * in some historic release.
1584 */
059ec3d9
PH
1585
1586/* Set context and tell client to go ahead, except in the case of TLS startup
1587on connection, where outputting anything now upsets the clients and tends to
1588make them disconnect. We need to have an explicit fflush() here, to force out
1589the response. Other smtp_printf() calls do not need it, because in non-TLS
1590mode, the fflush() happens when smtp_getc() is called. */
1591
817d9f57
JH
1592SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1593if (!tls_in.on_connect)
059ec3d9
PH
1594 {
1595 smtp_printf("220 TLS go ahead\r\n");
1596 fflush(smtp_out);
1597 }
1598
1599/* Now negotiate the TLS session. We put our own timer on it, since it seems
1600that the OpenSSL library doesn't. */
1601
817d9f57
JH
1602SSL_set_wfd(server_ssl, fileno(smtp_out));
1603SSL_set_rfd(server_ssl, fileno(smtp_in));
1604SSL_set_accept_state(server_ssl);
059ec3d9
PH
1605
1606DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1607
1608sigalrm_seen = FALSE;
1609if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
817d9f57 1610rc = SSL_accept(server_ssl);
059ec3d9
PH
1611alarm(0);
1612
1613if (rc <= 0)
1614 {
7199e1ee 1615 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
77bb000f
PP
1616 if (ERR_get_error() == 0)
1617 log_write(0, LOG_MAIN,
a053d125 1618 "TLS client disconnected cleanly (rejected our certificate?)");
059ec3d9
PH
1619 return FAIL;
1620 }
1621
1622DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1623
1624/* TLS has been set up. Adjust the input functions to read via TLS,
1625and initialize things. */
1626
817d9f57
JH
1627construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1628tls_in.cipher = cipherbuf;
059ec3d9
PH
1629
1630DEBUG(D_tls)
1631 {
1632 uschar buf[2048];
817d9f57 1633 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
059ec3d9
PH
1634 debug_printf("Shared ciphers: %s\n", buf);
1635 }
1636
9d1c15ef
JH
1637/* Record the certificate we presented */
1638 {
1639 X509 * crt = SSL_get_certificate(server_ssl);
1640 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1641 }
059ec3d9 1642
817d9f57
JH
1643/* Only used by the server-side tls (tls_in), including tls_getc.
1644 Client-side (tls_out) reads (seem to?) go via
1645 smtp_read_response()/ip_recv().
1646 Hence no need to duplicate for _in and _out.
1647 */
059ec3d9
PH
1648ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1649ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1650ssl_xfer_eof = ssl_xfer_error = 0;
1651
1652receive_getc = tls_getc;
1653receive_ungetc = tls_ungetc;
1654receive_feof = tls_feof;
1655receive_ferror = tls_ferror;
58eb016e 1656receive_smtp_buffered = tls_smtp_buffered;
059ec3d9 1657
817d9f57 1658tls_in.active = fileno(smtp_out);
059ec3d9
PH
1659return OK;
1660}
1661
1662
1663
1664
043b1248
JH
1665static int
1666tls_client_basic_ctx_init(SSL_CTX * ctx,
1667 host_item * host, smtp_transport_options_block * ob
1668#ifdef EXPERIMENTAL_CERTNAMES
1669 , tls_ext_ctx_cb * cbinfo
1670#endif
1671 )
1672{
1673int rc;
1674/* stick to the old behaviour for compatibility if tls_verify_certificates is
1675 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1676 the specified host patterns if one of them is defined */
1677
1678if ((!ob->tls_verify_hosts && !ob->tls_try_verify_hosts) ||
1679 (verify_check_host(&ob->tls_verify_hosts) == OK))
1680 {
1681 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1682 ob->tls_crl, host, FALSE, verify_callback_client)) != OK)
1683 return rc;
1684 client_verify_optional = FALSE;
1685
1686#ifdef EXPERIMENTAL_CERTNAMES
1687 if (ob->tls_verify_cert_hostnames)
1688 {
1689 if (!expand_check(ob->tls_verify_cert_hostnames,
1690 US"tls_verify_cert_hostnames",
1691 &cbinfo->verify_cert_hostnames))
1692 return FAIL;
1693 if (cbinfo->verify_cert_hostnames)
1694 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1695 cbinfo->verify_cert_hostnames);
1696 }
1697#endif
1698 }
1699else if (verify_check_host(&ob->tls_try_verify_hosts) == OK)
1700 {
1701 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1702 ob->tls_crl, host, TRUE, verify_callback_client)) != OK)
1703 return rc;
1704 client_verify_optional = TRUE;
1705 }
1706
1707return OK;
1708}
059ec3d9 1709
fde080a4
JH
1710
1711#ifdef EXPERIMENTAL_DANE
1712static int
fde080a4
JH
1713dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
1714{
1715dns_record * rr;
1716dns_scan dnss;
1717const char * hostnames[2] = { CS host->name, NULL };
1718int found = 0;
1719
1720if (DANESSL_init(ssl, NULL, hostnames) != 1)
1721 return tls_error(US"hostnames load", host, NULL);
1722
1723for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
1724 rr;
1725 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
1726 ) if (rr->type == T_TLSA)
1727 {
1728 uschar * p = rr->data;
1729 uint8_t usage, selector, mtype;
1730 const char * mdname;
1731
fde080a4 1732 usage = *p++;
133d2546
JH
1733
1734 /* Only DANE-TA(2) and DANE-EE(3) are supported */
1735 if (usage != 2 && usage != 3) continue;
1736
fde080a4
JH
1737 selector = *p++;
1738 mtype = *p++;
1739
1740 switch (mtype)
1741 {
133d2546
JH
1742 default: continue; /* Only match-types 0, 1, 2 are supported */
1743 case 0: mdname = NULL; break;
1744 case 1: mdname = "sha256"; break;
1745 case 2: mdname = "sha512"; break;
fde080a4
JH
1746 }
1747
133d2546 1748 found++;
fde080a4
JH
1749 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
1750 {
1751 default:
1752 case 0: /* action not taken */
1753 return tls_error(US"tlsa load", host, NULL);
1754 case 1: break;
1755 }
594706ea
JH
1756
1757 tls_out.tlsa_usage |= 1<<usage;
fde080a4
JH
1758 }
1759
1760if (found)
1761 return OK;
1762
133d2546 1763log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
fde080a4
JH
1764return FAIL;
1765}
1766#endif /*EXPERIMENTAL_DANE*/
1767
1768
1769
059ec3d9
PH
1770/*************************************************
1771* Start a TLS session in a client *
1772*************************************************/
1773
1774/* Called from the smtp transport after STARTTLS has been accepted.
1775
1776Argument:
1777 fd the fd of the connection
1778 host connected host (for messages)
83da1223 1779 addr the first address
a7538db1 1780 tb transport (always smtp)
0e66b3b6 1781 tlsa_dnsa tlsa lookup, if DANE, else null
059ec3d9
PH
1782
1783Returns: OK on success
1784 FAIL otherwise - note that tls_error() will not give DEFER
1785 because this is not a server
1786*/
1787
1788int
f5d78688 1789tls_client_start(int fd, host_item *host, address_item *addr,
0e66b3b6
JH
1790 transport_instance *tb
1791#ifdef EXPERIMENTAL_DANE
1792 , dns_answer * tlsa_dnsa
1793#endif
1794 )
059ec3d9 1795{
a7538db1
JH
1796smtp_transport_options_block * ob =
1797 (smtp_transport_options_block *)tb->options_block;
059ec3d9 1798static uschar txt[256];
868f5672
JH
1799uschar * expciphers;
1800X509 * server_cert;
059ec3d9 1801int rc;
817d9f57 1802static uschar cipherbuf[256];
043b1248
JH
1803
1804#ifndef DISABLE_OCSP
043b1248 1805BOOL request_ocsp = FALSE;
6634ac8d 1806BOOL require_ocsp = FALSE;
043b1248 1807#endif
043b1248
JH
1808
1809#ifdef EXPERIMENTAL_DANE
594706ea 1810tls_out.tlsa_usage = 0;
043b1248
JH
1811#endif
1812
f2de3a33 1813#ifndef DISABLE_OCSP
043b1248 1814 {
4f59c424
JH
1815# ifdef EXPERIMENTAL_DANE
1816 if ( tlsa_dnsa
1817 && ob->hosts_request_ocsp[0] == '*'
1818 && ob->hosts_request_ocsp[1] == '\0'
1819 )
1820 {
1821 /* Unchanged from default. Use a safer one under DANE */
1822 request_ocsp = TRUE;
1823 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
1824 " {= {4}{$tls_out_tlsa_usage}} } "
1825 " {*}{}}";
1826 }
1827# endif
1828
fca41d5a
JH
1829 if ((require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1830 NULL, host->name, host->address, NULL) == OK))
1831 request_ocsp = TRUE;
1832 else
fca41d5a 1833# ifdef EXPERIMENTAL_DANE
4f59c424 1834 if (!request_ocsp)
fca41d5a
JH
1835# endif
1836 request_ocsp = verify_check_this_host(&ob->hosts_request_ocsp,
1837 NULL, host->name, host->address, NULL) == OK;
043b1248 1838 }
f5d78688 1839#endif
059ec3d9 1840
65867078
JH
1841rc = tls_init(&client_ctx, host, NULL,
1842 ob->tls_certificate, ob->tls_privatekey,
f2de3a33 1843#ifndef DISABLE_OCSP
44662487 1844 (void *)(long)request_ocsp,
3f7eeb86 1845#endif
817d9f57 1846 addr, &client_static_cbinfo);
059ec3d9
PH
1847if (rc != OK) return rc;
1848
817d9f57 1849tls_out.certificate_verified = FALSE;
a2ff477a 1850client_verify_callback_called = FALSE;
059ec3d9 1851
65867078
JH
1852if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
1853 &expciphers))
059ec3d9
PH
1854 return FAIL;
1855
1856/* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1857are separated by underscores. So that I can use either form in my tests, and
1858also for general convenience, we turn underscores into hyphens here. */
1859
1860if (expciphers != NULL)
1861 {
1862 uschar *s = expciphers;
1863 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1864 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
817d9f57 1865 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
7199e1ee 1866 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
059ec3d9
PH
1867 }
1868
043b1248 1869#ifdef EXPERIMENTAL_DANE
0e66b3b6 1870if (tlsa_dnsa)
a63be306 1871 {
e5cccda9
JH
1872 SSL_CTX_set_verify(client_ctx, SSL_VERIFY_PEER, verify_callback_client_dane);
1873
043b1248 1874 if (!DANESSL_library_init())
b4161d10 1875 return tls_error(US"library init", host, NULL);
043b1248 1876 if (DANESSL_CTX_init(client_ctx) <= 0)
b4161d10 1877 return tls_error(US"context init", host, NULL);
043b1248
JH
1878 }
1879else
e51c7be2 1880
043b1248
JH
1881#endif
1882
1883 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob
e51c7be2 1884#ifdef EXPERIMENTAL_CERTNAMES
043b1248 1885 , client_static_cbinfo
e51c7be2 1886#endif
043b1248 1887 )) != OK)
65867078 1888 return rc;
059ec3d9 1889
65867078
JH
1890if ((client_ssl = SSL_new(client_ctx)) == NULL)
1891 return tls_error(US"SSL_new", host, NULL);
817d9f57
JH
1892SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1893SSL_set_fd(client_ssl, fd);
1894SSL_set_connect_state(client_ssl);
059ec3d9 1895
65867078 1896if (ob->tls_sni)
3f0945ff 1897 {
65867078 1898 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
3f0945ff 1899 return FAIL;
ec4b68e5 1900 if (tls_out.sni == NULL)
2c9a0e86
PP
1901 {
1902 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1903 }
ec4b68e5 1904 else if (!Ustrlen(tls_out.sni))
817d9f57 1905 tls_out.sni = NULL;
3f0945ff
PP
1906 else
1907 {
35731706 1908#ifdef EXIM_HAVE_OPENSSL_TLSEXT
817d9f57
JH
1909 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1910 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
35731706
PP
1911#else
1912 DEBUG(D_tls)
1913 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
02d9264f 1914 tls_out.sni);
35731706 1915#endif
3f0945ff
PP
1916 }
1917 }
1918
594706ea 1919#ifdef EXPERIMENTAL_DANE
0e66b3b6
JH
1920if (tlsa_dnsa)
1921 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa)) != OK)
594706ea
JH
1922 return rc;
1923#endif
1924
f2de3a33 1925#ifndef DISABLE_OCSP
f5d78688
JH
1926/* Request certificate status at connection-time. If the server
1927does OCSP stapling we will get the callback (set in tls_init()) */
b50c8b84 1928# ifdef EXPERIMENTAL_DANE
44662487
JH
1929if (request_ocsp)
1930 {
594706ea 1931 const uschar * s;
41afb5cb
JH
1932 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1933 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
594706ea
JH
1934 )
1935 { /* Re-eval now $tls_out_tlsa_usage is populated. If
1936 this means we avoid the OCSP request, we wasted the setup
1937 cost in tls_init(). */
1938 require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1939 NULL, host->name, host->address, NULL) == OK;
1940 request_ocsp = require_ocsp ? TRUE
1941 : verify_check_this_host(&ob->hosts_request_ocsp,
1942 NULL, host->name, host->address, NULL) == OK;
1943 }
1944 }
b50c8b84
JH
1945# endif
1946
594706ea
JH
1947if (request_ocsp)
1948 {
f5d78688 1949 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
44662487
JH
1950 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
1951 tls_out.ocsp = OCSP_NOT_RESP;
1952 }
f5d78688
JH
1953#endif
1954
774ef2d7
JH
1955#ifdef EXPERIMENTAL_EVENT
1956client_static_cbinfo->event_action = tb->event_action;
a7538db1 1957#endif
043b1248 1958
059ec3d9
PH
1959/* There doesn't seem to be a built-in timeout on connection. */
1960
1961DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1962sigalrm_seen = FALSE;
65867078 1963alarm(ob->command_timeout);
817d9f57 1964rc = SSL_connect(client_ssl);
059ec3d9
PH
1965alarm(0);
1966
043b1248 1967#ifdef EXPERIMENTAL_DANE
0e66b3b6 1968if (tlsa_dnsa)
fde080a4 1969 DANESSL_cleanup(client_ssl);
043b1248
JH
1970#endif
1971
059ec3d9 1972if (rc <= 0)
7199e1ee 1973 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
059ec3d9
PH
1974
1975DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1976
453a6645 1977/* Beware anonymous ciphers which lead to server_cert being NULL */
9d1c15ef 1978/*XXX server_cert is never freed... use X509_free() */
817d9f57 1979server_cert = SSL_get_peer_certificate (client_ssl);
453a6645
PP
1980if (server_cert)
1981 {
817d9f57 1982 tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
453a6645 1983 CS txt, sizeof(txt));
9d1c15ef 1984 tls_out.peerdn = txt; /*XXX a static buffer... */
453a6645
PP
1985 }
1986else
817d9f57 1987 tls_out.peerdn = NULL;
059ec3d9 1988
817d9f57
JH
1989construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
1990tls_out.cipher = cipherbuf;
059ec3d9 1991
9d1c15ef
JH
1992/* Record the certificate we presented */
1993 {
1994 X509 * crt = SSL_get_certificate(client_ssl);
1995 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
1996 }
1997
817d9f57 1998tls_out.active = fd;
059ec3d9
PH
1999return OK;
2000}
2001
2002
2003
2004
2005
2006/*************************************************
2007* TLS version of getc *
2008*************************************************/
2009
2010/* This gets the next byte from the TLS input buffer. If the buffer is empty,
2011it refills the buffer via the SSL reading function.
2012
2013Arguments: none
2014Returns: the next character or EOF
817d9f57
JH
2015
2016Only used by the server-side TLS.
059ec3d9
PH
2017*/
2018
2019int
2020tls_getc(void)
2021{
2022if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2023 {
2024 int error;
2025 int inbytes;
2026
817d9f57 2027 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
c80c5570 2028 ssl_xfer_buffer, ssl_xfer_buffer_size);
059ec3d9
PH
2029
2030 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
817d9f57
JH
2031 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
2032 error = SSL_get_error(server_ssl, inbytes);
059ec3d9
PH
2033 alarm(0);
2034
2035 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2036 closed down, not that the socket itself has been closed down. Revert to
2037 non-SSL handling. */
2038
2039 if (error == SSL_ERROR_ZERO_RETURN)
2040 {
2041 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2042
2043 receive_getc = smtp_getc;
2044 receive_ungetc = smtp_ungetc;
2045 receive_feof = smtp_feof;
2046 receive_ferror = smtp_ferror;
58eb016e 2047 receive_smtp_buffered = smtp_buffered;
059ec3d9 2048
817d9f57
JH
2049 SSL_free(server_ssl);
2050 server_ssl = NULL;
2051 tls_in.active = -1;
2052 tls_in.bits = 0;
2053 tls_in.cipher = NULL;
2054 tls_in.peerdn = NULL;
2055 tls_in.sni = NULL;
059ec3d9
PH
2056
2057 return smtp_getc();
2058 }
2059
2060 /* Handle genuine errors */
2061
ba084640
PP
2062 else if (error == SSL_ERROR_SSL)
2063 {
2064 ERR_error_string(ERR_get_error(), ssl_errstring);
89dd51cd 2065 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
ba084640
PP
2066 ssl_xfer_error = 1;
2067 return EOF;
2068 }
2069
059ec3d9
PH
2070 else if (error != SSL_ERROR_NONE)
2071 {
2072 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2073 ssl_xfer_error = 1;
2074 return EOF;
2075 }
c80c5570 2076
80a47a2c
TK
2077#ifndef DISABLE_DKIM
2078 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2079#endif
059ec3d9
PH
2080 ssl_xfer_buffer_hwm = inbytes;
2081 ssl_xfer_buffer_lwm = 0;
2082 }
2083
2084/* Something in the buffer; return next uschar */
2085
2086return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2087}
2088
2089
2090
2091/*************************************************
2092* Read bytes from TLS channel *
2093*************************************************/
2094
2095/*
2096Arguments:
2097 buff buffer of data
2098 len size of buffer
2099
2100Returns: the number of bytes read
2101 -1 after a failed read
817d9f57
JH
2102
2103Only used by the client-side TLS.
059ec3d9
PH
2104*/
2105
2106int
389ca47a 2107tls_read(BOOL is_server, uschar *buff, size_t len)
059ec3d9 2108{
389ca47a 2109SSL *ssl = is_server ? server_ssl : client_ssl;
059ec3d9
PH
2110int inbytes;
2111int error;
2112
389ca47a 2113DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
c80c5570 2114 buff, (unsigned int)len);
059ec3d9 2115
389ca47a
JH
2116inbytes = SSL_read(ssl, CS buff, len);
2117error = SSL_get_error(ssl, inbytes);
059ec3d9
PH
2118
2119if (error == SSL_ERROR_ZERO_RETURN)
2120 {
2121 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2122 return -1;
2123 }
2124else if (error != SSL_ERROR_NONE)
2125 {
2126 return -1;
2127 }
2128
2129return inbytes;
2130}
2131
2132
2133
2134
2135
2136/*************************************************
2137* Write bytes down TLS channel *
2138*************************************************/
2139
2140/*
2141Arguments:
817d9f57 2142 is_server channel specifier
059ec3d9
PH
2143 buff buffer of data
2144 len number of bytes
2145
2146Returns: the number of bytes after a successful write,
2147 -1 after a failed write
817d9f57
JH
2148
2149Used by both server-side and client-side TLS.
059ec3d9
PH
2150*/
2151
2152int
817d9f57 2153tls_write(BOOL is_server, const uschar *buff, size_t len)
059ec3d9
PH
2154{
2155int outbytes;
2156int error;
2157int left = len;
817d9f57 2158SSL *ssl = is_server ? server_ssl : client_ssl;
059ec3d9 2159
c80c5570 2160DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
059ec3d9
PH
2161while (left > 0)
2162 {
c80c5570 2163 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
059ec3d9
PH
2164 outbytes = SSL_write(ssl, CS buff, left);
2165 error = SSL_get_error(ssl, outbytes);
2166 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2167 switch (error)
2168 {
2169 case SSL_ERROR_SSL:
2170 ERR_error_string(ERR_get_error(), ssl_errstring);
2171 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2172 return -1;
2173
2174 case SSL_ERROR_NONE:
2175 left -= outbytes;
2176 buff += outbytes;
2177 break;
2178
2179 case SSL_ERROR_ZERO_RETURN:
2180 log_write(0, LOG_MAIN, "SSL channel closed on write");
2181 return -1;
2182
817d9f57
JH
2183 case SSL_ERROR_SYSCALL:
2184 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2185 sender_fullhost ? sender_fullhost : US"<unknown>",
2186 strerror(errno));
2187
059ec3d9
PH
2188 default:
2189 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2190 return -1;
2191 }
2192 }
2193return len;
2194}
2195
2196
2197
2198/*************************************************
2199* Close down a TLS session *
2200*************************************************/
2201
2202/* This is also called from within a delivery subprocess forked from the
2203daemon, to shut down the TLS library, without actually doing a shutdown (which
2204would tamper with the SSL session in the parent process).
2205
2206Arguments: TRUE if SSL_shutdown is to be called
2207Returns: nothing
817d9f57
JH
2208
2209Used by both server-side and client-side TLS.
059ec3d9
PH
2210*/
2211
2212void
817d9f57 2213tls_close(BOOL is_server, BOOL shutdown)
059ec3d9 2214{
817d9f57 2215SSL **sslp = is_server ? &server_ssl : &client_ssl;
389ca47a 2216int *fdp = is_server ? &tls_in.active : &tls_out.active;
817d9f57
JH
2217
2218if (*fdp < 0) return; /* TLS was not active */
059ec3d9
PH
2219
2220if (shutdown)
2221 {
2222 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
817d9f57 2223 SSL_shutdown(*sslp);
059ec3d9
PH
2224 }
2225
817d9f57
JH
2226SSL_free(*sslp);
2227*sslp = NULL;
059ec3d9 2228
817d9f57 2229*fdp = -1;
059ec3d9
PH
2230}
2231
36f12725
NM
2232
2233
2234
2235/*************************************************
3375e053
PP
2236* Let tls_require_ciphers be checked at startup *
2237*************************************************/
2238
2239/* The tls_require_ciphers option, if set, must be something which the
2240library can parse.
2241
2242Returns: NULL on success, or error message
2243*/
2244
2245uschar *
2246tls_validate_require_cipher(void)
2247{
2248SSL_CTX *ctx;
2249uschar *s, *expciphers, *err;
2250
2251/* this duplicates from tls_init(), we need a better "init just global
2252state, for no specific purpose" singleton function of our own */
2253
2254SSL_load_error_strings();
2255OpenSSL_add_ssl_algorithms();
2256#if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2257/* SHA256 is becoming ever more popular. This makes sure it gets added to the
2258list of available digests. */
2259EVP_add_digest(EVP_sha256());
2260#endif
2261
2262if (!(tls_require_ciphers && *tls_require_ciphers))
2263 return NULL;
2264
2265if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2266 return US"failed to expand tls_require_ciphers";
2267
2268if (!(expciphers && *expciphers))
2269 return NULL;
2270
2271/* normalisation ripped from above */
2272s = expciphers;
2273while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2274
2275err = NULL;
2276
2277ctx = SSL_CTX_new(SSLv23_server_method());
2278if (!ctx)
2279 {
2280 ERR_error_string(ERR_get_error(), ssl_errstring);
2281 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2282 }
2283
2284DEBUG(D_tls)
2285 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2286
2287if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2288 {
2289 ERR_error_string(ERR_get_error(), ssl_errstring);
2290 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
2291 }
2292
2293SSL_CTX_free(ctx);
2294
2295return err;
2296}
2297
2298
2299
2300
2301/*************************************************
36f12725
NM
2302* Report the library versions. *
2303*************************************************/
2304
2305/* There have historically been some issues with binary compatibility in
2306OpenSSL libraries; if Exim (like many other applications) is built against
2307one version of OpenSSL but the run-time linker picks up another version,
2308it can result in serious failures, including crashing with a SIGSEGV. So
2309report the version found by the compiler and the run-time version.
2310
f64a1e23
PP
2311Note: some OS vendors backport security fixes without changing the version
2312number/string, and the version date remains unchanged. The _build_ date
2313will change, so we can more usefully assist with version diagnosis by also
2314reporting the build date.
2315
36f12725
NM
2316Arguments: a FILE* to print the results to
2317Returns: nothing
2318*/
2319
2320void
2321tls_version_report(FILE *f)
2322{
754a0503 2323fprintf(f, "Library version: OpenSSL: Compile: %s\n"
f64a1e23
PP
2324 " Runtime: %s\n"
2325 " : %s\n",
754a0503 2326 OPENSSL_VERSION_TEXT,
f64a1e23
PP
2327 SSLeay_version(SSLEAY_VERSION),
2328 SSLeay_version(SSLEAY_BUILT_ON));
2329/* third line is 38 characters for the %s and the line is 73 chars long;
2330the OpenSSL output includes a "built on: " prefix already. */
36f12725
NM
2331}
2332
9e3331ea
TK
2333
2334
2335
2336/*************************************************
17c76198 2337* Random number generation *
9e3331ea
TK
2338*************************************************/
2339
2340/* Pseudo-random number generation. The result is not expected to be
2341cryptographically strong but not so weak that someone will shoot themselves
2342in the foot using it as a nonce in input in some email header scheme or
2343whatever weirdness they'll twist this into. The result should handle fork()
2344and avoid repeating sequences. OpenSSL handles that for us.
2345
2346Arguments:
2347 max range maximum
2348Returns a random number in range [0, max-1]
2349*/
2350
2351int
17c76198 2352vaguely_random_number(int max)
9e3331ea
TK
2353{
2354unsigned int r;
2355int i, needed_len;
de6135a0
PP
2356static pid_t pidlast = 0;
2357pid_t pidnow;
9e3331ea
TK
2358uschar *p;
2359uschar smallbuf[sizeof(r)];
2360
2361if (max <= 1)
2362 return 0;
2363
de6135a0
PP
2364pidnow = getpid();
2365if (pidnow != pidlast)
2366 {
2367 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2368 is unique for each thread", this doesn't apparently apply across processes,
2369 so our own warning from vaguely_random_number_fallback() applies here too.
2370 Fix per PostgreSQL. */
2371 if (pidlast != 0)
2372 RAND_cleanup();
2373 pidlast = pidnow;
2374 }
2375
9e3331ea
TK
2376/* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2377if (!RAND_status())
2378 {
2379 randstuff r;
2380 gettimeofday(&r.tv, NULL);
2381 r.p = getpid();
2382
2383 RAND_seed((uschar *)(&r), sizeof(r));
2384 }
2385/* We're after pseudo-random, not random; if we still don't have enough data
2386in the internal PRNG then our options are limited. We could sleep and hope
2387for entropy to come along (prayer technique) but if the system is so depleted
2388in the first place then something is likely to just keep taking it. Instead,
2389we'll just take whatever little bit of pseudo-random we can still manage to
2390get. */
2391
2392needed_len = sizeof(r);
2393/* Don't take 8 times more entropy than needed if int is 8 octets and we were
2394asked for a number less than 10. */
2395for (r = max, i = 0; r; ++i)
2396 r >>= 1;
2397i = (i + 7) / 8;
2398if (i < needed_len)
2399 needed_len = i;
2400
2401/* We do not care if crypto-strong */
17c76198
PP
2402i = RAND_pseudo_bytes(smallbuf, needed_len);
2403if (i < 0)
2404 {
2405 DEBUG(D_all)
2406 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2407 return vaguely_random_number_fallback(max);
2408 }
2409
9e3331ea
TK
2410r = 0;
2411for (p = smallbuf; needed_len; --needed_len, ++p)
2412 {
2413 r *= 256;
2414 r += *p;
2415 }
2416
2417/* We don't particularly care about weighted results; if someone wants
2418smooth distribution and cares enough then they should submit a patch then. */
2419return r % max;
2420}
2421
77bb000f
PP
2422
2423
2424
2425/*************************************************
2426* OpenSSL option parse *
2427*************************************************/
2428
2429/* Parse one option for tls_openssl_options_parse below
2430
2431Arguments:
2432 name one option name
2433 value place to store a value for it
2434Returns success or failure in parsing
2435*/
2436
2437struct exim_openssl_option {
2438 uschar *name;
2439 long value;
2440};
2441/* We could use a macro to expand, but we need the ifdef and not all the
2442options document which version they were introduced in. Policylet: include
2443all options unless explicitly for DTLS, let the administrator choose which
2444to apply.
2445
2446This list is current as of:
e2fbf4a2
PP
2447 ==> 1.0.1b <==
2448Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2449*/
77bb000f
PP
2450static struct exim_openssl_option exim_openssl_options[] = {
2451/* KEEP SORTED ALPHABETICALLY! */
2452#ifdef SSL_OP_ALL
73a46702 2453 { US"all", SSL_OP_ALL },
77bb000f
PP
2454#endif
2455#ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
73a46702 2456 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
77bb000f
PP
2457#endif
2458#ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
73a46702 2459 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
77bb000f
PP
2460#endif
2461#ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
73a46702 2462 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
77bb000f
PP
2463#endif
2464#ifdef SSL_OP_EPHEMERAL_RSA
73a46702 2465 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
77bb000f
PP
2466#endif
2467#ifdef SSL_OP_LEGACY_SERVER_CONNECT
73a46702 2468 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
77bb000f
PP
2469#endif
2470#ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
73a46702 2471 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
77bb000f
PP
2472#endif
2473#ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
73a46702 2474 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
77bb000f
PP
2475#endif
2476#ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
73a46702 2477 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
77bb000f
PP
2478#endif
2479#ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
73a46702 2480 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
77bb000f
PP
2481#endif
2482#ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
73a46702 2483 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
77bb000f 2484#endif
c80c5570
PP
2485#ifdef SSL_OP_NO_COMPRESSION
2486 { US"no_compression", SSL_OP_NO_COMPRESSION },
2487#endif
77bb000f 2488#ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
73a46702 2489 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
77bb000f 2490#endif
c0c7b2da
PP
2491#ifdef SSL_OP_NO_SSLv2
2492 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2493#endif
2494#ifdef SSL_OP_NO_SSLv3
2495 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2496#endif
2497#ifdef SSL_OP_NO_TICKET
2498 { US"no_ticket", SSL_OP_NO_TICKET },
2499#endif
2500#ifdef SSL_OP_NO_TLSv1
2501 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2502#endif
c80c5570
PP
2503#ifdef SSL_OP_NO_TLSv1_1
2504#if SSL_OP_NO_TLSv1_1 == 0x00000400L
2505 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2506#warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2507#else
2508 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2509#endif
2510#endif
2511#ifdef SSL_OP_NO_TLSv1_2
2512 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2513#endif
e2fbf4a2
PP
2514#ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2515 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2516#endif
77bb000f 2517#ifdef SSL_OP_SINGLE_DH_USE
73a46702 2518 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
77bb000f
PP
2519#endif
2520#ifdef SSL_OP_SINGLE_ECDH_USE
73a46702 2521 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
77bb000f
PP
2522#endif
2523#ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
73a46702 2524 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
77bb000f
PP
2525#endif
2526#ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
73a46702 2527 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
77bb000f
PP
2528#endif
2529#ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
73a46702 2530 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
77bb000f
PP
2531#endif
2532#ifdef SSL_OP_TLS_D5_BUG
73a46702 2533 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
77bb000f
PP
2534#endif
2535#ifdef SSL_OP_TLS_ROLLBACK_BUG
73a46702 2536 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
77bb000f
PP
2537#endif
2538};
2539static int exim_openssl_options_size =
2540 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2541
c80c5570 2542
77bb000f
PP
2543static BOOL
2544tls_openssl_one_option_parse(uschar *name, long *value)
2545{
2546int first = 0;
2547int last = exim_openssl_options_size;
2548while (last > first)
2549 {
2550 int middle = (first + last)/2;
2551 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2552 if (c == 0)
2553 {
2554 *value = exim_openssl_options[middle].value;
2555 return TRUE;
2556 }
2557 else if (c > 0)
2558 first = middle + 1;
2559 else
2560 last = middle;
2561 }
2562return FALSE;
2563}
2564
2565
2566
2567
2568/*************************************************
2569* OpenSSL option parsing logic *
2570*************************************************/
2571
2572/* OpenSSL has a number of compatibility options which an administrator might
2573reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2574we look like log_selector.
2575
2576Arguments:
2577 option_spec the administrator-supplied string of options
2578 results ptr to long storage for the options bitmap
2579Returns success or failure
2580*/
2581
2582BOOL
2583tls_openssl_options_parse(uschar *option_spec, long *results)
2584{
2585long result, item;
2586uschar *s, *end;
2587uschar keep_c;
2588BOOL adding, item_parsed;
2589
0e944a0d 2590result = 0L;
b1770b6e 2591/* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
da3ad30d 2592 * from default because it increases BEAST susceptibility. */
f0f5a555
PP
2593#ifdef SSL_OP_NO_SSLv2
2594result |= SSL_OP_NO_SSLv2;
2595#endif
77bb000f
PP
2596
2597if (option_spec == NULL)
2598 {
2599 *results = result;
2600 return TRUE;
2601 }
2602
2603for (s=option_spec; *s != '\0'; /**/)
2604 {
2605 while (isspace(*s)) ++s;
2606 if (*s == '\0')
2607 break;
2608 if (*s != '+' && *s != '-')
2609 {
2610 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
0e944a0d 2611 "+ or - expected but found \"%s\"\n", s);
77bb000f
PP
2612 return FALSE;
2613 }
2614 adding = *s++ == '+';
2615 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2616 keep_c = *end;
2617 *end = '\0';
2618 item_parsed = tls_openssl_one_option_parse(s, &item);
2619 if (!item_parsed)
2620 {
0e944a0d 2621 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
77bb000f
PP
2622 return FALSE;
2623 }
2624 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2625 adding ? "adding" : "removing", result, item, s);
2626 if (adding)
2627 result |= item;
2628 else
2629 result &= ~item;
2630 *end = keep_c;
2631 s = end;
2632 }
2633
2634*results = result;
2635return TRUE;
2636}
2637
9d1c15ef
JH
2638/* vi: aw ai sw=2
2639*/
059ec3d9 2640/* End of tls-openssl.c */